Substitution model#GTR: Generalised time reversible in biology
Guided tissue regeneration, a dental procedure
General theory of relativity, the current standard theory in physics describing gravitation

D.I.C.E. (TV series), a catchphrase
Global Technical Regulation(s) of the World Forum for Harmonization of Vehicle Regulations
GTR-18A, also DGTR-18A and Smokey Sam, US SAM training rocket
GTR Group, the company presently known as Mad Catz
Green tree reservoir, flooded forest

After competing successfully in 1997, the race car was upgraded in 1998 for the 24 Hours of Le Mans and renamed the CLK LM. Following the construction of the CLK LMs and the CLK GTR road cars, the project would end in 1999 by being replaced by the Mercedes-Benz CLR Le Mans prototype.

As the Deutsche Tourenwagen Meisterschaft/International Touring Car Championship had folded in late 1996, with both remaining competitors Opel and Alfa Romeo leaving due to the high costs of their 4WD designs, Mercedes-Benz had no top series to compete in. With the success of the BPR Global GT Series leading to the FIA taking over and turning it into an international series known as the FIA GT Championship, Mercedes-Benz saw an opportunity to go against manufacturers like Porsche and Ferrari.
Following the design that Porsche had laid out with their 911 homologation special, Mercedes-AMG was tasked by Mercedes-Benz with creating an extreme racing car that still maintained some elements of a normal street legal car. AMG's designers created a car which shared some design elements with the Mercedes-Benz CLK, yet had all the standard features of a racing car underneath. A Mercedes-Benz M120 V12 engine would be at the heart of the car, mounted behind the cockpit. The bodywork would be made entirely of carbon fiber, and would feature many aerodynamic design elements and cooling openings in order to survive on the race track.
To test the CLK GTR before the first chassis were built, Mercedes-AMG actually took an unusual measure. Through secrecy, Mercedes-AMG was able to purchase a disused McLaren F1 GTR, the defending BPR GT series champion, from Larbre Comptition. This purchase first allowed Mercedes-AMG to see the kind of lap times that their competitors could run, to serve as a measurement of the CLK GTR's abilities. However, more importantly, Mercedes-AMG set about modifying this F1 GTR by attaching bodywork that was meant to go on the CLK GTR. Mercedes-Benz also used their own LS600 6.0 liter engine in place of the BMW V12 unit. This allowed Mercedes-AMG to be able to perfect the aerodynamics of the car before it had even been built.
Upon completion of the first two prototypes a mere 128 days after the initial drawings had been made, the CLK GTRs were entered into the 1997 FIA GT Championship season, debuting at the season-opener at one of Mercedes-Benz's home tracks, the Hockenheimring. Unfortunately the new cars were not able to shine, as brake problems eliminated one car after five laps, and the other finished over 20 laps behind the winning McLaren. However, by the next round at Silverstone, the CLK GTR began to show its pace, finishing less than a second behind the winning McLaren. By the fourth round, returning to Germany for the Nrburgring, a third CLK GTR was added to the team. In this race, Mercedes-Benz successfully outperformed the fleet of McLarens, taking first and second places. The team would finish out the season with five more wins, at A1-Ring, Suzuka, Donington, Sebring, and Laguna Seca, allowing them to secure the team championship as well as the drivers championship for Bernd Schneider.
Mercedes-Benz would use the CLK GTR for the first two rounds of the 1998 season before upgrading to the CLK LM. However privateer team Persson Motorsport would campaign two CLK GTRs throughout the entire season, taking a best finish of second at Oschersleben before finishing the year third in the teams championship.
Initially the CLK-GTR's V12 engine produced approximately 600 hp (450 kW) before developments during the 1997 season increased this to 630 hp (470 kW). Persson Motorsport's CLK GTRs remained at this power output as Mercedes-AMG had moved to development of the V8 in the CLK LM.